In one well known method and apparatus of making fibers from a molten inorganic material, such as glass, a plurality of small orifices or orifice tips are formed in the base of a molten glass chamber or bushing. The molten material flows from the bushing out of the orifice tips forming cones at the end of the tips. When the temperature of the molten material at these cones is properly controlled, continuous fibers or filaments can be drawn from the tips of the cones.
Cooling means are commonly utilized for controlling the temperature of the cones in order to effectively and accurately regulate the transition of the molten glass viscosity. One prior art manner of controlling the temperature of the cones is to place a tube adjacent to the cones and to cause a cooling medium such as water to flow through the tube at a rate necessary to maintain a desired cone temperature. The molten glass viscosity conventionally is first maintained at a relatively low level and a very fluid condition proximate the bottom of the chamber adjacent the discharge orifices in order to promote an effective flow therein and a full uninterrupted discharge. Thereafter the viscosity is brought to relatively higher viscosities following discharge from the orifices to govern the attenuation of the fluid stream into a filament of apt dimensions and to increase its coherency thereby minimizing breakage.
Conventional cooling means which have heretofore been utilized proximate the area of the fluid glass stream as it emerges from the orifices include either tubes carrying water or other liquid coolants and/or solid metal bars positioned transverse to the length of the bushing. The tubes or bars have traditionally been composed of noble or similar exotic metals or alloys thereof. These materials effectively endure the high temperatures and corrosive vapors encountered proximate the bushing. As is well known, the environment around the cooling tubes including the area around the cooling tube supports, is harsh in terms of high temperature, corrosiveness caused by the temperature, volatiles from the molten material and water spray typically used around the bushing. At times, depending on the material used, this harsh environment deteriorates the cooling tubes or bars requiring one or more to be replaced at more or less periodic time intervals.
Previously the materials used include platinum, gold, silver, palladium, and the like. However, the costs of such materials are exorbitant for extensive factory operations.